For the animations specifically, it's using Motion (fka Framer Motion) Javascript library. If you describe some animations from the site to an LLM and ask it to use Framer motion, you get very similar results. The creator likely just prompted for a while until they were happy with the outcome.
Yup, strange to see people still don’t understand LLMs massively speed up coding greenfield pet projects. Anytime you see a bee web app it’s better to assume AI use rather than not anymore.
I'm not familiar enough with this animation library to answer that. Someone could be very used to this type of website and just copy paste things they've done before.